Many of the people who take care of U.S. federal lands and wildlife refuges say their jobs have become more dangerous, according to a new survey.

Public Employees for Environmental Responsibility (PEER), a nonprofit that represents government staff, released the results of the survey on Feb. 2. The group gathered responses from 104 out of 302 managers of the Fish and Wildlife Service's federal refuge and 364 employees of the Bureau of Land Management (BLM), including scientists, archaeologists and public lands managers.

Of those who responded, 1 in 5 federal refuge managers reported that members of their families or staff "have been threatened or harassed in connection with resource management policies. "Nearly half (48 percent) of BLM staff who responded said they face threats to their safety due to resource management issues, according to PEER. [See Photos of All US National Parks]

The report comes ahead of this month's criminal trials for seven of the militants who occupied eastern Oregon's Malheur National Wildlife Refuge last year. The armed occupation lasted for 41 days in a bid to get the U.S. government to give up control of federal lands. Other militants involved were acquitted of federal conspiracy and weapons charges last year, which many environmentalists and other advocates saw as a setback for the protection of public lands.

"The legacy of the Malheur occupation seems to be that despite greater spending on security there is heightened insecurity for both visitors and refuge staff," PEER Executive Director Jeff Ruch said in a statement.

Among wildlife refuge managers, 64 percent said that security costs in their refuge are higher than they were five years ago. At the same time, 63 percent said they feel visitors are not as safe as they were five years ago.

Eighty-two percent of refuge managers and 70 percent BLM respondents also expressed that the Malheur acquittals were making their jobs more dangerous.

"Although militias have not taken over BLM facilities, its employees reflect a siege mentality," Ruch said. "It is a sad state of affairs when federal botanists and archaeologists fear attack for doing their jobs."

Ruch said PEER is now compiling all of 2016's official reports of threats or violence against federal resource management agencies.